I set Play to add Replaygain information to 400 CD's, the track gain is correct but all the albums end up with the same level of Album gain. (-7.40 in my case) so I am assuming that if you batch Replaygain you get an Albums value of all the Albums that were selected. Is this how its supposed to work?

Adding the gain on each individual album would take me forever but on the few I have done the Album,ms vales are now as I expected. I also found that the Replaygain Clear option does not effect the tags, I check this by using the "Tag" application.

The way I've set up replay gain scanning is that all selected tracks will be scanned as an album. As you've discovered this isn't ideal for adding RG to a large collection that is well-tagged, but it eliminates the possibility of miscalculating RG based on bad assumptions about which tracks constitute an album.

As far as the clear option goes, I will delve into the source. I can't remember off the top of my head if Play only zeroes its local RG values or if it pushes the changes out the files as well.